Radio Frequency Interference (RFI) fix needed

[2019RamInSC]

If you are a ARRL member they have some tech support resources. To include local help. Try this.

http://www.arrl.org/technical-information-service

Good luck.

 

[Ramabam]

Make sure your power leads run off the battery direct (both fused), and not connected to any cigerate type connector.

 

[goldtr8]

Big difference between grounding and bonding. You need to bond your body to the driveline and the bed of the truck. Then you need to install common mode chokes at the antenna feedpoints as common mode is present on your mobile antennas due to the imbalance to the ground plane. Too much to write down but I suggest you go to K0GB's website K0BG.com to read thru the stuff on his website. You can contact me in a PM if you want. KD8NNU been there and done that and RAMS are noisy beasts.

 

[njjeff201]

I remember one year Ford had alternator noise probably on AM radios… not sure. We added a cap to the alternator, made sure all grounds including radio chassis & antenna were grounded. You may need to contact an automotive radio specialist store if they still exist if Ram blows you off or Google. N2ZNN

 

[Tahoebronco]

Is the fuel pump electrically driven? If so, would a ferrite filter on the power wires there be helpful?

 

[Mister Luck]

 

[steveb3906]

I would do this:

First add a ground wire from the radio metal chassis to a good ground point on the truck.
Measure the resistance between the antenna ground point and your radio ground point, should be close to zero to 3 ohms.

Can you hear the interference on a handheld radio? You might be able to pinpoint the noise by sticking the antenna into different areas.

Second, take another piece of coax and try rerouting loosely around the truck on a different path to see if the static noise is less. (You might have routed the coax next to the "magic" noise box.)

Install a 50-ohm terminator (dummy load) on the radio. Does it still have the interference? Points more towards the noise coming in on the DC power wires.

You could try a better grade of coax like RG-142 double shielded.

-Steve WA6OXN

 

[Mister Luck]

In physics interference is the addition of two or more waves that results in a new wave pattern interference usually referrers to the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same frequency.

This form of interference can occur whenever a wave can propagate from a source to a destination by two or more paths of different length .

Two or more paths can only be used to produce interference when there is a fixed phase relation between them, but in this case the interference generated is the same as with a single source

( see Huygen’s Principal )

 

[Sailing Santa]

Big difference between grounding and bonding. You need to bond your body to the driveline and the bed of the truck. Then you need to install common mode chokes at the antenna feedpoints as common mode is present on your mobile antennas due to the imbalance to the ground plane. Too much to write down but I suggest you go to K0GB's website K0BG.com to read thru the stuff on his website. You can contact me in a PM if you want. KD8NNU been there and done that and RAMS are noisy beasts.

Done all this. Thanks. Still searching for cause.

 

[RayL]

I have a 2016 RAM 1500 5.7 L gasser and have no RFI, But I have lots of experience with other vehicles on HF ops. Does the intererence sound like a constant speed motor (whine, etc), or does it change speed as you accelerate? If varible, my first suspect would be the fuel pump. I doubt Chrysler has a kit or fix for it. You usually have to get help or dig it out yourself. Can you hear the RFI on a battery powered radio" If so, that's a clue it is being radiated. Grounding the tail pipe to the frame at the engine and the rear end, has also helped me in the past. It's a good 10 to 14 MHz (prox) 1/4 wave antenna. Ray, W4BYG

 

[NH2500guy]

I found that I had noise on the ground from some aftermarket LEDs I installed on the aux switches. Noise was so bad couldn't use fm radio at all, also in a 18 Cummins diesel 2500. Went away after putting ferrite chokes on the grounds and feeds to the Led lights.
Worked for me.
The only other thing that comes to mind is that maybe one of your batteries may be on the way out and causing funky things to be happening with the way the alternator is charging the batteries, or switching charging on and off rapidly, causing rf interference. May want to look for any corrosion on any connections and check the batteries internal resistance and load test or analyze cell balance. Had a couple newer batteries do strange things like that on my old duramax.

Best of luck and hope you figure it out.

 

[Mister Luck]

Should be a simple problem but for some reason it isn’t..
Santa is checking his list twice ,
he”s going to find it sooner or later.

 

[Mister Luck]

With all the grounding points for potential RFI , have you ever thought about EMI ? electromagnetic interference doesn’t have a distinct polarity so why wouldn’t the resonance of your radio create it’s own interference through your grounding system essentially amplified ?

Do you know anything about this?
If you protected your ground wire from back feeding to your radio or even reduce the voltage would that change the interference wave length ?

 

[Mister Luck]

Doesn’t this basically act like a diode ?

IBNF10 - Metra Noise Filter For Filtering Induced Noise

IBNF10 - Metra Noise Filter For Filtering Induced Noise

www.wearecb.com

As in this video has it a diode with a coil

Combatting Circuit Interference (EMI/RFI) [Mastering Meters and Advanced Electrical Diagnostics]

Need some advice on combatting circuit interference for EMI and RFI? The Delphi Training Series breaks it down for you. To see the full webinar on Mastering ...

m.youtube.com

The diode only acts on AC current and coil acts on DC.

I see now if FCA or MOPAR had a kit it would already be the nominal size diode.

 

[Dusty]

I'm thinking it may be the injectors. There are, if memory serves me right, up to 6 injection events per compression stroke. I can't think of anything else that would cause the noise.

Yeah, that's what I was thinking, the only thing that I can think of producing a pulse-type noise related to the accelerator pedal.

FWIW, on 5.7s there are RFI capacitors located behind each cylinder head (between the head and the firewall). Have no idea about Cummins'.

There are two hams in the club that own Rams and running 144-440. I'm not sure they run any HF, but I've never heard them complain about anything, either.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 066633 miles.

 

[Dusty]

Is this the engine that has a non-metal valve cover with rubber isolated valve cover bolts?

I am not familiar with the new Cummins, but if the injectors are under the valve cover, I think the injector wiring is part of the valve cover gasket which is a semi-hard plastic. I'm thinking there's little to no shielding for the injectors and circuit wiring.

Best regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 066633 miles.

 

[Mister Luck]

I’ve read the fuel heater grid can become contaminated and spark current

 

[Mister Luck]

I recently discovered my iPhone interfered with my radio transmissions but only in certain frequencies.
It was as if I was keying up without touching the radio at all just close proximity.
Solution : Turning off iPhone when operating Radio

 

[Sailing Santa]

More digging.

From an article I found -

With the use of high pressure injectors it takes a 100V pulse to actually fire
the injector. There is also some back EMF from the solenoids as the pulse ends
and the solenoid opens. Unfortunately the diodes to clamp the back EMF are
usually located in the Injector Driver Module (IDM) where they protect the IDM
from the back EMF transient. By that time the couple feet of wire connecting
the two has radiated the emission.

Place the clamping diodes at the injectors, shield the wires, and round the
edges of the pulse that fires the solenoid and the problem should subside. Not
recommended for appliance operators/drivers or vehicles in warranty.

— so, my guess here is find the diode values that Ram uses and start there. A diode of the same value in parallel across the tops of each injector along with a ferrite core on the wires and shielding.

 

[Caboverbob]

I have an RCI 6300F150 in my Cummins powered '17 2500. I get some noise during acceleration that can be heard on my external speaker, but nothing transmitted. I have ferrites on coax (passenger side) and power leads (driver side). Breedlove mount on headache rack with bond straps to cab (3rd brake light mount screws) and rack, and rack to bed. I even have a 40a inline rfi filter under the hood. Despite all of this, the noise is still there.